For the three-month period ended in February, the iPhone was the most popular smartphone in the U.S., with a 38.9 percent market share — up 3.9 percentage points from the November quarter. And with a 38.9 percent share, iOS was the second-most-popular smartphone platform, also up 3.9 percentage points from the preceding period.

Welcome gains for Apple, particularly for their origins. The growth of iOS, for example, appears to have been achieved largely at the expense of Android. Google’s mobile OS lost two percentage points during the period comScore surveyed, falling to 51.7 percent from 53.7 percent. BlackBerry slipped as well, losing 1.9 points and ending the period at 5.4 percent (caveat: BlackBerry didn’t begin selling its new Z10 handset in the U.S. until late March). Together, the two companies lost 3.9 points of platform share, precisely the amount Apple gained.

In the smartphone hardware market, Apple’s gains also appear to stem largely from the losses of its top Android rivals — save one. HTC, Motorola and LG all saw their market share decline in the three months ended in February. Only Samsung managed to capture additional share — a single point, lifting it to 21.3 percent from 20.3 percent. That’s about a quarter of the growth Apple charted.

Now, Samsung is likely to see a more significant increase in the current quarter, thanks to the launch of the Galaxy S4, but it certainly won’t be enough to close the gap with Apple. If anything, it will simply offset the market-share losses of other Android handset makers.

In other words, Apple’s in no danger of forfeiting its lead in the U.S. smartphone hardware market anytime soon, and in the platform market, its position is secure as well, thanks to that unshaken Android-iOS duopoly, which commands a combined 90.6 percent market share.

Update: Horace Dediu has some great insight into these metrics over at Asymco.

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